Development of Electromagnetic Wave Absorbers Having the Ultra Wide Bandwidth Absorbing Center Frequency

超宽带宽吸收中心频率电磁波吸收体的研制

基本信息

批准号：
14550309
负责人：
YOSHIKADO Shinzo
金额：
$ 1.66万
依托单位：
DOSHISHA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

We developed conductor-backed single layered electromagnetic wave absorbers made of ferrite composites (spinel-type Ni-Zn ferrite, SiO_2) having the ultra wide bandwidth absorbing center fFrequency. The density and the hardness are improved by adding B_2O_3, but the conductance value increases with increasing the density. It degrades the absorption characteristics of a metal-backed single layered electromagnetic wave absorber in the high-frequency region. The conductivity was reduced by adding oxides such as CoO, NiO or MnCO_3. The complex permeability, however, decreased for the ferrite composites with added CoO or NiO but did not change for that with added MnCO_3. Composite electromagnetic wave absorbers fabricated by adding B2O_3 and NiO or MnCO_3 operated in the frequency region up to 6 GHz without decreasing both the density and the hardness. The ferrite composite with added B_2O_3 and MnCO_3 had a wide selection range of the absorbing center frequency by simply changing the thick … More ness while maintaining the absorption characteristics.Electromagnetic wave absorbers coated with ITO thin film with the required center absorbing frequency can be made by choosing the suitable thicknesses of both the film and the ferrite composite without changing the composition of the absorber. Absorbing characteristic of electromagnetic wave absorbers added CoO or NiO having required center absorbing frequency below approximately 5GHz can be achieved by coating of ITO thin film with the suitable thicknesses or resistivity without changing the composition.The absorption characteristics of ferrite composites using fine powders of SiO_2 with the average grain size of approximately 30 nm, 12 nm or 7 nm were improved compared with those of ferrite composites using SiO_2 powders of the average grain size of approximately 29 mm in the low frequency region below 1 GHz. Furthermore, grain size dependence of ferrite composites of fine powders of Ni-Zn ferrite (20 mol%) and SiO_2 (80 mol%) with the normal size such as 29 mm was investigated by the simulation using the model. Result of simulation shows that electromagnetic waves above 90 % in the wide frequency region similar so Ni-Zn ferrite is absorbed in the low frequency region below 1 GHz and is absorbed in the high frequency region above 1 GHz by changing the thicknesses of the absorbers. Less

我们开发了由铁氧体复合材料（尖晶石型Ni-Zn铁氧体，SiO_2）制成的导体背衬单层电磁波吸收体，具有超宽带宽吸收中心f频率，通过添加B_2O_3提高了密度和硬度，但电导值增加。随着密度的增加，金属背衬单层电磁波吸收体的吸收特性降低，电导率降低。添加CoO、NiO或MnCO_3等氧化物的铁氧体复合材料的复磁导率降低，但添加MnCO_3的铁氧体复合材料的磁导率没有变化。添加B_2O_3的铁氧体复合材料在高达6GHz的频率范围内不会降低密度和硬度。 MnCO_3和MnCO_3在保持吸收特性的同时，只需改变厚度即可获得较宽的吸收中心频率选择范围。通过选择两者合适的厚度，可以制成具有所需中心吸收频率的ITO薄膜涂层电磁波吸收体在不改变吸收体成分的情况下，通过涂覆CoO或NiO，可以实现所要求的中心吸收频率低于约5GHz的电磁波吸收体的吸收特性。在不改变成分的情况下获得合适厚度或电阻率的ITO薄膜。平均晶粒尺寸约为30 nm、12 nm或7 nm的SiO_2细粉的铁氧体复合材料的吸收特性比使用SiO_2的铁氧体复合材料有所改善在低于1 GHz的低频区域中，粉末的平均晶粒尺寸约为29毫米此外，Ni-Zn细粉的铁氧体复合材料的晶粒尺寸依赖性。使用该模型对正常尺寸（如29 mm）的铁氧体（20 mol%）和SiO_2（80 mol%）进行了研究。模拟结果表明，90%以上的电磁波在与Ni-Zn类似的宽频区域内。通过改变吸收体的厚度，铁氧体在1GHz以下的低频区域被吸收，在1GHz以上的高频区域被吸收。